1. Field of the Invention
The present invention relates to switches and routers at an edge of a network, and, in particular, to associating their ports with physical locations of devices attached to those ports.
2. Description of the Related Art
Networks of general purpose computer systems and specialized devices connected by external communication links are well known and widely used in commerce. The networks often include one or more network devices that facilitate the passage of information between the computer systems and devices. A network node is a network device or computer or specialized device connected by the communication links. An end node is a network node that is configured to originate or terminate communications over the network. An intermediate network node facilitates the passage of data between end nodes.
Communications between nodes are typically effected by exchanging discrete packets of data. Information is exchanged within data packets according to one or more of many well known, new or still developing protocols. In this context, a protocol consists of a set of rules defining how the nodes interact with each other based on information sent over the communication links. Each packet typically comprises 1] header information associated with a particular protocol, and 2] payload information that follows the header information and contains information that may be processed independently of that particular protocol. The header includes information such as the source of the packet, its destination, the length of the payload, and other properties used by the protocol. Often, the data in the payload for the particular protocol includes a header and payload for a different protocol associated with a different layer of detail for information exchange.
The headers included in a packet traversing multiple heterogeneous networks, such as the Internet, typically include a physical (layer 1) header, a data-link (layer 2) header, an internetwork (layer 3) header and a transport (layer 4) header, as defined by the Open Systems Interconnection (OSI) Reference Model. The OSI Reference Model is generally described in more detail in Section 1.1 of the reference book entitled Interconnections Second Edition, by Radia Perlman, published September 1999, which is hereby incorporated by reference as though fully set forth herein.
The internetwork header provides information defining the source and destination address within the network. Notably, the path may span multiple physical links. The internetwork header may be formatted according to the Internet Protocol (IP), which specifies IP addresses of both a source and destination node at the end points of the logical path. Thus, the packet may “hop” from node to node along its logical path until it reaches the end node assigned to the destination IP address stored in the packet's internetwork header.
Routers and switches are intermediate network nodes that determine which communication link or links to employ to support the progress of data packets through the network. A network node that determines which links to employ based on information in the internetwork header (layer 3) is called a router.
In many buildings, a router or switch with multiple network interfaces, called ports, is housed in a closet. Cables are laid as communication links from that closet through one or more walls and floors to outlets, called jacks, distributed across one portion of the building, such as one storey or one section of one storey. The cables' terminals in the closet are connected to ports on the router or switch. The cables are out of sight once laid and can not be tracked easily from the closet to the jacks. When a device is to be connected to the network, it is placed in a location in the building and a cable connects it to a convenient jack. In the closet, it is not necessarily apparent which cable terminal and port is associated with the jack and connected device. With only one device connected, power levels on the cable and port can be used to indicate the active port and associate that port with the connected device. With dozens of devices connected it is considerably more difficult to determine which port is associated with which device.
Building and maintaining maps of the physical wiring port layouts is a necessary task for information technology (IT) groups during network establishment and maintenance. People rarely move cables once they are installed, but lots of effort is needed to run and label cables, as well as any additions and changes to the wiring. However, over the occupancy life of a building many adds, moves, and changes occur in the network. To keep current the mapping of jacks to closet terminals and intermediate node ports, continuous, time-consuming and labor intensive manual updates are made. Computer programs and databases have been developed to record this information, such as Cisco Discovery Protocol (CDP) available from Cisco Systems, Inc., of San Jose, Calif. However, the source of the information still involves persons at each end of the hidden cable, either one person walking back and forth or two people working together, and manually plugging and unplugging cables from ports, and devices and test equipment (such as ringers) from jacks. If an update is omitted it can take days and months until the omission becomes apparent, often at an inopportune moment, such as during a crisis caused by equipment failure.
The most popular current method is to statically tag the jacks at the office/cube site and the corresponding rack/port in the wiring closet when the cable is pulled. This method does not have a self-correcting check when wires are crossed, tags lost, or new wires laid. To maintain the database, testing of each port for a connection to a specific device is done when needed. This manual testing is time consuming as the device at the each end must be manually verified for the mapping to be correct.
In the wireless world, location is determined by the end device association to the localized access point. This does not work in wired environments because the switches do not have to be in the vicinity of the end user. Some devices have geo-location systems, such as the Global Positioning System (GPS). However, these devices typically do not have the spatial resolution needed to distinguish cubicles and rooms from each other.
Furthermore, with the increased use of internet telephony, an emergency call can be placed. Without reliable information on the physical location of the end device where the call was placed, emergency responders cannot be directed automatically to the correct room to provide aid. Human life and health can depend on the accuracy of the information that maps ports to jacks.
Based on the foregoing, there is a clear need for techniques that automatically and quickly determine a physical location of devices connected to a port on an intermediate network node.